Biochemical and metabolic features of microbial ecology in host tissues are the broad concerns of this project. Specific aims focus on identifying, measuring and evaluating the function of substances that cytoplasmic granules of phagocytes, especially polymorphonuclear granulocytes (PMN), may contribute to the intravacuolar environment of phagocytized bacteria. During the new grant period we will study: 1. Antimicrobial factors in specific granules and azurophils isolated from human PMN with velocity centrifugation. 2. Granule composition and function in PMN of patients with impaired intraleukocytic bacterial killing. 3. The kinetics of degranulation of specific and azurophil granules. 4. Heterogeneity and functions of granule proteases. 5. Comparative morphology, metabolism and antimicrobial functions of human, rabbit and chicken PMN.